The present invention relates to plug construction for electric cord sets, and, more particularly, to a particular plug construction having a low insertion force at low temperatures and improved resistance to the insertion of an oversized blade into the hot wire side of a female plug.
Among the requirements for electric cord sets is that such equipment not be adversely affected by temperatures at which such devices are normally used. Many cord sets are produced using moldable plastic materials for the plugs. These plastic materials become increasingly rigid as the temperature decreases. As the plugs become rigid it becomes very difficult, if not impossible, to insert a male plug into a female socket. A requirement of standards organizations such as the Underwriter's Laboratories Inc., is that the low temperature insertion force not exceed a predetermined standard. An additional standard required by the Underwriter's Laboratories and other standards agencies, is that the electricity carrying "hot" side, the narrower of the two blade openings of the female plug, be able to resist insertion of an over-sized blade when subjected to a pre-established degree of force. In order to obtain approval of a plug construction, it is necessary that a female plug be capable of passing both standards established by the industry.